Return to KLUBNL.PL main page

rsgb_lf_group
[Top] [All Lists]

Re: LF: OPERA - why it's less data than normal CW ?

To: [email protected]
Subject: Re: LF: OPERA - why it's less data than normal CW ?
From: Andy Talbot <[email protected]>
Date: Tue, 3 Jan 2012 17:55:51 +0000
Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:content-transfer-encoding; bh=M9xt6qp9ku3Q2yy9oGvim86iEXSTwDRuVXK2bA8wKDI=; b=d063LJtEgVrsplr69EXBGrnSSMFErfevIPad++t7NfUHIfP3eoyIx0dcqQwax05MNX oYEfYTQdng4b5QZ41t5SW7kLmrMC12SgIZt+KGiu6kfMraYeXtd8Pw1azZRSwTPtw5+l o92KXC2TM6mP7suV2MPz+7QBvWKXsS9gusVQc=
In-reply-to: <[email protected]>
References: <780955996.1040888.1325583040480.JavaMail.fmail@mwmweb057> <CAA8k23TCT9qzrQykuWVa3AD0uOd_cPbd7XbKP7bXONWrpo=TYw@mail.gmail.com> <[email protected]>
Reply-to: [email protected]
Sender: [email protected]
Until I deleted every last trace of the software after discovering it
was sending IP packets, I had started analysing the Tx sequence to see
if it made any sense

For any given sub-mode, the Tx slots are all equal length, so allocate
a 0 and1 to each Tx state.
If you do an autocorrelation on the resulting sequence, (by XORing a
delayed version of the pattern with itself) some interesting longer
sequences show up - always an even number of 1's' and 0's' for
example.
It almost has a vague Manchester Coding feel to it.

But all analysis is stopped and will permanently stay so until a
version appears that will not send IP packets.
It was much easier to 'crack'  WSJT coding - just a case of reading
the source code :-)

'jnt


On 3 January 2012 17:42, Alberto di Bene <[email protected]> wrote:
> On 1/3/2012 10:36 AM, Andy Talbot wrote:
>
> If 'someone' would publish the innards of that mode, a simple Tx only
> keyer could surely be developed, and te mode woue be useful
>
> And maybe somebody could even adventure in writing an Rx program...
> but of course the protocol needs to be completely open source for this.
>
> 73  Alberto  I2PHD
>
>


<Prev in Thread] Current Thread [Next in Thread>